Do you, perchance, pbum a hardware store (or even a general drygoods and sundries shop) on your way to work? You should be able to pick up a decent screwdriver for $10 or so.

If you can get the same colour, Frank won’t even notice that it’s not the regular one, and you won’t have to tell him the truth.

If it’s a different colour, you can tell him what happened and then show him that you’ve bought a new screwdriver to replace the one you’ve lost. In that case, he’ll be impressed with your initiative.

$10 may be a couple of hours’ wages, but it’s a small price to pay for not getting yelled at. Good luck!